config: make the upload limit configurable

config/config.exs

@@ -49,6 +49,7 @@ config :pleroma, :instance,
   name: "Pleroma",
   email: "example@example.com",
   limit: 5000,
+  upload_limit: 16_000_000,
   registrations_open: true,
   federating: true
 

lib/pleroma/web/endpoint.ex

@@ -34,7 +34,8 @@ defmodule Pleroma.Web.Endpoint do
     Plug.Parsers,
     parsers: [:urlencoded, :multipart, :json],
     pass: ["*/*"],
-    json_decoder: Jason
+    json_decoder: Jason,
+    length: Application.get_env(:pleroma, :instance) |> Keyword.get(:upload_limit)
   )
 
   plug(Plug.MethodOverride)